1. Technical Field
The present invention relates to a paper-based wet friction material of an automotive auto transmission, and more particularly, to a paper-based wet friction material of an automotive auto transmission which is formed in a multilayer to improve noise and vibration characteristics, heat resistance, wear resistance, compression resistance, and oil absorbency.
2. Description of the Related Art
A clutch of a transmission used as a power transfer means of a vehicle is classified into a manual type and an auto type depending on a system.
The manual type has a function of a dry contact mechanism using a part which regulates power of an engine, while the auto type has a hydraulic torque converter and a wet contact mechanism using transmission oil within a trans/trans axle which is used for regulating and controlling power.
In North America, most vehicles use an automotive auto transmission and large vehicles such as truck and bus increasingly use the automotive auto transmission. The use of the automotive auto transmission is suddenly spreading as the use of vehicles is suddenly increased and a quality of vehicles is improved.
A paper disc which is used as a clutch part of the automotive auto transmission needs to be excellent in physical properties such as friction and abrasion properties, durability, and impregnation porosity. In particular, the clutch of the automotive auto transmission is operated within the transmission oil, and therefore needs to have high friction property, wear resistance, durability, and the like even at high temperature.
Until now, as a wet clutch material, paper, sintered copper (sintered Cu), resin, graphite, and the like have been used, but as a friction material for vehicles, paper mainly tends to be used.
The paper disc is made of an inorganic filler, a thermosetting resin (phenol, epoxy, melamine resin), and the like, using pulp as the basis, in which it has been known that a kind and an added amount of inorganic filler have a great effect on the friction property of the paper disc.
However, the paper disc is expensive and does not satisfy friction property, wear resistance, durability, and the like at a high temperature. Therefore, a necessity for development of a paper disc which solves the above problem has been increased.